This invention relates to a system and method for generating a topographical map or digital elevation model of ground terrain from two images of the ground terrain. Topographical mapping is the process of generating three-dimensional height models of ground terrain. The most common method for topographical mapping is stereoscopy or stereoimaging in which the parallax or disparity between common features of a pair of images are proportional to the topographic height of the features. By identifying a number of such matching features, the height of the terrain can be calculated at these points and a smooth surface can be interpolated through them to create a three-dimensional model.
For stereoimaging to work properly, the imaging sensors must be positioned at a specific orientation relative to one another. The viewing axes of the sensors must be mutually parallel and perpendicular to the imaginary line that connects the sensor positions. The major drawback of stereoimaging systems is the constraint placed on the relative orientation of the sensors. The present invention improves upon the stereoimaging systems in that it places no constraint on the orientations of the sensors. The method and system works for images taken from any point of view and orientation.